عنوان مقاله [English]
The objectives of this study were to compare fertility between heatsynch and estradoublesynch protocols in fresh Holstein dairy cows. Holstein cows with normal ovary and uterus (n= 191, yielding more than 30 kg of milk/d and parity 3.2±1.1) were randomly assigned into two experimental groups, including 1- heatsynch (n=96) , GnRH-7d-PGF2α-24h-EB-48H-TAI or 2) estradoublesynch (n=86), PGF2α-2d-GnRH-7d-PGF2α-24h-EB-48h- TAI. Results showed that estradoublesynch increased the percentage of cows diagnosed pregnant cows at 32 and 60 d after AI (P < 0.05). Conception rate was greater in estradoublesynch compared to heatsynch protocol at d 60 after TAI. Pregnancy loss was lower in estradoublesynch compared to heatsynch protocol (P < 0.05; 8.81 vs. 19.23 % for heatsynch and estradoublesynch protocols, respectively). Mean (± SEM) diameter (mm) of ovulatory follicle at the time of TAI was larger in heatsynch (19.2±0.32) than estradoublesynch (17.1±0.19). In conclusion, estradoublesynch resulted in younger ovulatory follicle compared to heatsynch and causes higher conception rate as well as lower pregnancy loss in this group.
1- Caraviello, D., K. Weigel., P. Fricke., M. C. Wiltbank., M. Florent and N. Cook, et al. 2006. Survey of management practices on reproductive performance of dairy cattle on large US commercial farms. Journal of Dairy Science 89:4723-4735.
2- Cirit, Ü., K. Ak and I. K. Ileri, 2007. New strategies to improve the efficiency of the Ovsynch protocol in primiparous dairy cows. Bulletin of the Veterinary Institute in Pulawy 51:47–51.
3- Dirandeh, E., H. Kohram and A. Zare Shahneh. 2009. GnRH injection before artificial insemination (AI) alters follicle dynamics in Iranian Holstein cows. African Journal of Biotechnology 15:3672-3676.
4- Dirandeh, E. 2014. Starting Ovsynch protocol on day 6 of first postpartum estrous cycle increased fertility in dairy cows by affecting ovarian response during heat stress. Animal Reproduction Science 149:135-140.
5- Dirandeh, E., A. Rezaei Roodbari and M. G. Colazo. 2015a. Double-Ovsynch, compared with presynch with or without GnRH, improves fertility in heat-stressed lactating dairy cows. Theriogenology 83:438-443.
6- Dirandeh, E., A. Rezaei Roodbari., M. Gholizadeh., H. Deldar., M. Kazemifard and M. G. Colazo. 2015b. Administration of prostaglandin F2α 14 d before initiating a G6G or a G7G timed-AI protocol increased circulating progesterone prior to AI and reduced pregnancy loss in multiparous Holstein cows. Journal of Dairy Science 98:5414–5421
7- Galvao, K.N., J. E. Santos., R. L. Cerri., R. C. Chebel., H. M. Rutigliano., R. G. Bruno and R. C. Bicalho. 2007. Evaluation of methods of resynchronization for insemination in cows of unknown pregnancy status. Journal of Dairy Science 90:4240–4252.
8- Garrett, J. E., R. D. Geisert., M. T. Zavy., L. K. Gries., R. P. Wettemann and D. S. Buchanan. 1988. Effect of exogenous progesterone on prostaglandin F2α release and the interestrous interval in the bovine. Prostaglandins 36:85–96.
9- Mann, G. E., G. E. Lamming., R. S. Robinson and D. C. Wathes. 1999. The regulation of interferon-τ production and uterine hormone Progesterone and embryonic survival in cows E37 receptors during early pregnancy. Journal of Reproduction and Fertility 54:317–328.
10- Mirmahmoudi, R. and B. S. Prakash. 2012. The endocrine changes, timing of ovulation and efficacy of the Doublesynch protocol in the Murrah buffaloes (Bubalus bubalis). General and Comparative Endocrinology 177:153–9.
11- Mirmahmoudi, R., S. Souri and B. S. Prakash, 2014. Endocrine changes, timing of ovulation, ovarian follicular growth and efficacy of a novel protocol (Estradoublesynch) for synchronization of ovulation and TAI in Murrah buffaloes (Bubalus bubalis). Theriogenology 81:237–42.
12- Moreira, F., R. L. de la Sota., T. Diaz and W. W. Thatcher. 2000. Effect of day of the estrous cycle at the initiation of a timed artificial insemination protocol on reproductive responses in dairy heifers. Journal of Animal Science 78:1568–1576.
13- Öztürk, Ö.A., U. Cirit., A. Baran and K. Ak. 2010. Is Doublesynch protocol a new alternative for timed artificial insemination in anestrous dairy cows. Theriogenology 73:568–76.
14- Perry, G.A., T. W. Geary., M. C. Lucy and M. F. Smith. 2002. Effect of follicle size at the time of induced ovulation on luteal function and fertility. Procedding Western Section of American Society of Animal Science 55:45–48.
15- Pursley, J.R., M. O. Mee and M. C. Wiltbank. 1995. Synchronization of ovulation in dairy cows using PGF2a and GnRH. Theriogenology 44:915-923.
16- Souza, A.H., A. Gumen., E. P. Silva., A. P. Cunha., J. N. Guenther and C. M. Peto, et al. 2007. Supplementation with estradiol-17 beta before the last gonadotropin-releasing hormone injection of the Ovsynch protocol in lactating dairy cows. Journal of Dairy Science 90:4623–34.
17- Vasconcelos, J. L. M., R.W. Silcox., G. J. M. Rosa., J. R. Pursley and M. C. Wiltbank. 1999. Synchronization rate, size of the ovulatory follicle, and pregnancy rate after synchronization of ovulation beginning on different days of the estrous cycle in lactating dairy cows. Theriogenology 52:1067–1078.
18- Wiltbank, M. C and R. J. Pursley. 2014. The cow as an induced ovulator: Timed AI after synchronization of ovulation. Theriogenology 81:170–185.
19- Yamada, K., T. Nakao and N. Mihara. 1999. Synchronization of ovulation and fixed-time insemination for improvement of conception rate in dairy herds with poor estrus detection efficiency. Journal of Reproduction and Development 45(1) :51-55.